Structural stability of CuAlOunder pressure.

Structural properties of CuAlO, which was recently argued to show unusual suppression of the Jahn-Teller distortions by the spin-orbit coupling, are investigated under pressures up to 6 GPa. Analysis of x-ray powder diffraction experiments shows that CuAlOgets unstable and decomposes onto CuO and AlOat pressures ∼6 GPa and temperature ∼1000 K. This finding is complemented by the density-functional theory ++ spin-orbit coupling calculations, which demonstrate that this instability is partially driven by a (relatively) large compressibility of strongly Jahn-Teller distorted CuO.